Which steps are mandatory to enable Direct NFS?
1. Mount all required file systems using the kernel NFS driver.
2. Create an oranfstab file containing the attributes for each NFS server to be accessed
using Direct NFS.
3. Replace the ODM library libodm11.so_stub with libodm11.so.
A.
2 and 3
B.
1 and 3
C.
1 and 2
D.
1, 2 and 3
B is correct:
http://www.oracle.com/technetwork/articles/directnfsclient-11gr1-twp-129785.pdf
To use Direct NFS Client, the NFS file systems must first be mounted and available
over regular NFS mounts. The mount options used in mounting the file systems are
not relevant, as Direct NFS Client manages the configuration after installation. Direct
NFS Client can use a new configuration file ‘oranfstab’ or the mount tab file (/etc/mtab
on Linux) to determine the mount point settings for NFS storage devices. It may be
preferrable to configure the Direct NFS Client in the mount tab file if you have multiple
Oracle installations that use the same NAS devices.
Oracle Database will access files stored on the NFS server directly through the integrated Direct NFS Client eliminating the overhead imposed by the operating system kernel NFS.
Finally, to enable Direct NFS Client, you must replace the standard Oracle Disk Manager (ODM) library with one that supports Direct NFS Client.